Terrestrial communications systems continue to provide higher and higher speed multimedia (e.g., voice, data, video, images, etc.) services to end-users. Such services (e.g., Third Generation (3G) and Fourth Generation (4G) services) can also accommodate differentiated quality of service (QoS) across various applications. To facilitate this, terrestrial architectures are moving towards an end-to-end all-Internet Protocol (IP) architecture that unifies all services, including voice, over the IP bearer. In parallel, mobile satellite systems (MSS) are being designed to complement and/or coexist with terrestrial coverage depending on spectrum sharing rules and operator choice. With the advances in processing power of desktop computers, the average user has grown accustomed to sophisticated applications (e.g., streaming video, radio broadcasts, video games, etc.), which place tremendous strain on network resources. Internet services, as well as other IP services, rely on protocols and networking architectures that offer great flexibility and robustness; however, such infrastructure may be inefficient in transporting IP traffic, which can result in large user response time, particularly if the traffic has to traverse an intermediary network with a relatively large latency (e.g., a satellite network). To promote greater adoption of data communications services, the telecommunications industry, from manufacturers to service providers, has agreed at great expense and effort to develop standards for communications protocols that underlie the various services and features.
Satellite systems, however, pose unique design challenges over terrestrial systems. That is, mobile satellite systems have different attributes that make terrestrial designs either not applicable or inefficient for satellite systems. For example, satellite systems are characterized by long delays (as long as 260 ms one-way) between a user terminal device and a base station compared to the relatively shorter delays (e.g., millisecond or less) in terrestrial cellular systems—which implies that protocols on the satellite links have to be enhanced to minimize impact of long propagation delays. Additionally, satellite links typically have smaller link margins than terrestrial links for a given user-terminal power amplifier and antenna characteristics; this implies that higher spectral efficiency and power efficiency are needed in satellite links. Moreover, the satellite transmission or channel resources represent limited resources, where the deployment of additional transmission resources is significantly more expensive, difficult and time consuming as compared with terrestrial radio resources. Accordingly, the transmission resources of a satellite system must be used efficiently to maximize the available bandwidth, in order to provide the required quality of service for the extensive and diverse assortment of service applications available to the mobile user, and to maximize the number of potential users in a system without adversely affecting the quality of service.
An IP Multicast service is a point to multipoint service, where hosts or users join an IP multicast session by using host-router protocols, such as Internet Group Management Protocol (IGMP). Traditional wireless IP networks are typically deployed based on unicast architectures and protocols. Accordingly, under a unicast framework or infrastructure, for a multicast session, each IP packet of the multicast session must be transmitted individually to each participating host via a wireless link (e.g., in a unicast or point to point manner). Such a multicast session, therefore, would utilize as many radio resources as there are hosts participating in the multicast session, which inefficiently consumes extensive radio resources for a multicast session.
What is needed, therefore, is an approach for efficient use of radio and spectral resources for multicast services in terrestrial wireless and satellite mobile communications systems. What is further needed is an approach for efficient use of radio resources for secure transmission of multicast data streams in a mobile satellite system. There is a further need for a process that facilitates optimal designation of physical layer attributes (e.g., modulation, coding, power, etc.), in a manner providing for further spectral efficiency in the use of satellite or radio resources.